Main memory reconfiguration

ABSTRACT

An apparatus and a method for reconfiguring an m-module m-way interleaved main memory store to a k-way interleaved configuration where k equals m/2. In a main memory store having m modules and operating in an n-way interleaved configuration L additional reconfiguration modes allow the isolation of any one bad module in the upper half of the memory addressing range, thus giving assurance of operation in the lower half of the memory addressing range. The remaining lower half of the memory system remains addressable so that diagnostic procedures may be run in that portion of memory simultaneously with the running of user programs on the other portion of memory.

United States Patent 1191 Curley et al.

[ 1 Mar. 12, 1974 [54] MAIN MEMORY RECONFIGURATION 3,626,374 12/1971 Chinlund 340/1725 '5 Inventors: J L. y Sud y; enjamin 3,686,640 12/1972 Andersen et al 340/l7-.5

S. Franklin, Boston, both of Mass; P E P I J Wallace A. Martland, Nashua, N.H.; '"f 'f Thomas J. Donahue, Hudson; Louis jssmam P R Id V. Cornaro, Billerica, both of Mass. 32? 'g or o as rasmos Una [73] Assignee: Honeywell Information Systems Inc.,

Waltham, Mass. 57] ABSTRACT [22] Flled: 1972 An apparatus and a method for reconfiguring an m- 2 Appl 295 417 module m-way interleaved main memory store to a k-way interleaved configuration where k equals m/2. In a main memory store having in modules and operat- [52] US. Cl. 340/1725 g in an y interleaved configuration L additional [51] '3" 3/00 reconfiguration modes allow the isolation of any one [58] Fleld of Search 340/1725 bad module in the upper half of the memory address ing range, thus giving assurance of operation in the [56] References C'ted lower half of the memory addressing range. The re- UNITED STATES PATENTS maining lower half of the memory system remains ad- 3,106,698 10/1963 Unger 340 1725 dressable so that diagnostic procedures may be run in 3,268,875 8/1966 Schaffer 340/1725 that portion of memory simultaneously with the run- 3,564,505 2/1971 Finnila et aim 3 ning of user programs on the other portion of mem- 3,629,842 12/1971 Taylor 340/1725 my 3,680,058 7/1972 DeSantis et al 340/1725 3,681,757 12/1972 Allen et a1. 340/1725 6 Claims, 8 Drawing Figures MODULE MODULE 2 3 MODULE MODULE 0 '1 FROM MSS RELATED APPLICATIONS The following applications are included herein by reference:

1. Buffer Store invented by .l. L. Curley, T. .l. Donahue, W. A. Martland, and B. S. Franklin, filed on the same date as the instant application, having Ser. No. 295,301 and assigned to the same assignee named herein.

2. Variable Masking for Segmented Memory" invented by Wallace A. Martland and John L. Curley, filed on same date as the instant application, having Ser. No. 295,303 and assigned to the same assignee named herein.

3. Override Hardware for Main Store Sequencer invented by Thomas J. Donahue, filed on same date as the instant application, having Ser. No. 295,418 and assigned to the same assignee named herein.

4. Main Memory Sequencer" invented by T. J. Donahue, John L. Curley, Benjamin S. Franklin, W. A. Martland, and L. V. Cornaro, filed on same date as the instant invention, having Ser. No. 295,331 and assigned to the same assignee named herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to computer storage systems and more particularly to a storage system having four memory modules capable of dynamic operation under program control in a four-way interleaved addressing scheme or a two-way interleaved addressing scheme,

2. Description of the Prior Art In order to improve the performance of the computer system, improvements in the basic speed of the components and circuitry and also improvements through functional organization have been resorted to. In order to enhance the speed of a computer system through functional organization, one technique that has been resorted to is to divide main memory store into a number of storage modules that can be accessed in parallel. Moreover each module of main memory store may be organized into independent arrays. For example, in a two module system, module 1 contains array number I which contains all the even numbered addresses and module 2 contains the second array which contains all the odd numbered addresses. Storage locations therefore alternate between the two arrays and in this particular instance the storage has been arranged in what is known as a two-way interleaved storage. Storage systems may be n-way interleaved; however there is a practical upper limit imposed by hardware costs.

One major disadvantage of the interleaved addressing scheme is that failure in any one memory module would disable the entire system. It is desirable therefore to have more than one mode of interleaved addressing so that a system operating in an m-way interleaved mode may be reconfigured to operate in a k-way interleaved mode. Moreover it is also desirable that any portion of main store be addressable regardless of the configuration of the interleaved addressing scheme.

One prior art scheme describing memory interleaving and memory reconfiguration utilizing plug boards for reconfiguring memory is described on pages 16-25 of A Guide to the IBM System/370 Model published and copyrighted by IBM in 1970 and 1971.

OBJ ECTS It is an object, therefore, of the invention to provide an improved computer storage system.

It is another object of the invention to provide a stor age system having m main memory modules which may have an m and k-way interleaved addressing scheme.

It is still another object of the invention to provide a dynamic interleaved addressing scheme for m main memory modules that may be combined under program control in a predetermined number of groups, R,,

3, 1 interleaved addressing configuration m or k when k equals m/Z.

Other objects and advantages of the invention will become apparent from the following description of the preferred embodiment of the invention when read in conjunction with the drawings contained herewith.

SUMMARY OF THE INVENTION The foregoing objects are achieved according to one embodiment of the instant invention by providing typically four main memory modules that may be arranged in a four-way or two-way interleaved addressing scheme. Normal operation of the system is in the fourway interleaved configuration. With failure in any one memory module, reconfiguration under program control produces a two-way interleaved system with at least half the memory capacity of the original system (addresses 0 to X/2'l, where X equals original memory capacity) assured to function correctly. The remaining half of the memory system (addresses X/2 to X-l remains addressable but access to this portion of the storage will produce unspecified results. The reten tion of full addressing to all of memory is a substantial aid to diagnostic procedures.

There are typically three configuration modes although other numbers may be used; the normal mode of operation is the no-error situation wherein the modules are arranged in the four-way interleaved addressing scheme. There are two reconfiguration modes R1 and R2 which allow the isolation of any one bad module in the upper half of the memory addressing range. giving assurance of operation in the lower half of the memory addressing range. This reconfiguration scheme has the additional benefit in that, of the six possible two-module failure situations, two of those combinations (i.e., failure ofO and 1 module or failure of 2 and 3 module) can be reconfigured to give the same reduced capability as a I module failure case. Therefore in all of these cases reconfiguration R1 or R2 gives assurred memory operation in the lower half of memory and moreover addressability to all of memory, upper and lower.

BRIEF DESCRIPTION OF THE DRAWINGS This invention will be described with reference to the accompanying drawings wherein:

FIGS. lA-IC are block diagrams illustrating the three configuration modes.

FIG. 2 is a detailed logic block diagram ofa logic network for achieving the three configuration modes of main memory.

FIG. 3 is a format of address bits used to address main memory store in the normal and reconfigured mode.

FIGS. 4A4C illustrate in block diagram format the organization of main memory modules in. each of the three configurations.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGS. lA-lC and FIGS. 4A-4C there is shown three configurations of main memory store (MMS). FIGS. 1A and 4A are the normal mode of operation and illustrate modules -3 in a four-way interleaved addressing scheme. By referring to FIG. 4A it is seen that there are two address spaces 1, 2 shown for each of two 36 bit words in MMS module 0. Similarly word address spaces 3 and 4 are in MMS, module 1, word address spaces 5 and 6 in MMS module 2, and word address spaces 7 and 8 in MMS; module 3. The cycle then begins over again, with word address spaces 9 and 10 in MMS module 0 and so on for any number of words. In the normal mode of operation address space bits 27 and 28 are utilized to address any module in MMS. (See FIG. 3). In FIG. 3 it is shown that in normal operation bit positions 27 and 28 in combination are used for module select. Referring now once again to FIG. 4A it is shown that the combination of bit 27- not and bit 28-not addresses MMS the combination of bit 27-not and bit 28 addresses MMS,; the combination of bit 27 and 28-not addresses MMSg; and the combination of bits 27 and 28 addresses MMS Referring to FIGS. 18 and 4B (valid only for a two megabyte system) there is shown the reconfigured mode R1. In this mode a fault is located in either modules 2 or 3 or in both modules 2 and 3 and hence are reconfigured so that modules 2 and 3 are in the upper half of the memory addressing range. Note by referring to FIG. 48 that each 36 bit word is organized so that words 1, 2, 3, and 4 are still in MMS and MMS respectively but that words 5, 6, 7, and 8 are no longer in MMS and MMS respectively but in MMS,, and MMS respectively. Note also that bit positions 11 and 28 are utilized to address any MMS module in reconfigured state R] or R2. Hence in reconfigured state R1 bits lI-not and 28-not address module 0; bits ll-not and 28 address module 1, bits 11 and 28-not address module 2; and bits 11 and 28 address module 3.

FIGS. 1C and 4C illustrate in block diagram format reconfigured mode R2 wherein a fault is located in module 0 or module 1 or in module 0 and module 1. Note by referring to FIG. 4C that the organization of words usable by the user has shifted so that words 1, 2, 3, and 4 are in MMS and MMS;; respectively and also words 5, 6, 7, and 8 are in MMS and MMS respectively. This procedure is repeated for any number of words up to the capacity of the storage system.

Referring now to FIG. 3 there is shown the format for addressing modules and words in MMS both in the normal and reconfigured state. This format is for a two megabyte capacity system although similar type formats may be utilized for other capacities requiring a less number of bits for lower capacities, and a large number of bits for larger capacities. By examining FIG. 3 it will be seen that with the exception of the module select bits the word address bits to MMS are shifted to the left by one position in the reconfigured mode when compared to the normal mode. This represents a binary order of magnitude shift and permits addressing of the same total memory space addressed under normal mode, but relocating the user usable words into good memory i.e., that half of memory which does not have a fault. This permits the address words to progress through reconfigured memory in a similar manner as they did in memory in the normal state.

Referring now to FIG. 2 it will be shown how a reconfigured mode is selected, and how a particular module in the reconfigured mode is addressed. As an example, assume that the system is operating in reconfigured mode R1. Signals indicating the reconfigured mode desired are applied to pins 801, 802, and 803. If reconfigured mode R1 is desired, a signal UNRCl 18 applied to pin 802 is high, whereas if reconfigured mode R2 is desired a signal UNRCN21S is applied to pin 803. Signal UNR241S applied to pin 801 indicates, when it is high, that the CPU has requested that the memory be reconfigured in a two four-way interleaved mode. If, as in this example, reconfigured state R1 is desired then the signal from the CPU UNRCllS is high at pin 802. The high signal is distributed through AND gate 805, amplifier 808, AND gate 810, amplifier 812, AND gate 817, and amplifier 822 to generate signal NRECYll indicating that the memory is reconfigured into reconfiguration state Rl. To address any memory module in the reconfigured state of this two megabyte main memory store system, bits 11 and 28 are required in predetermined combinations discussed supra; FIGS. 48 and 4C show the combination of bits for addressing a particular module in the reconfigured state. Carrying through the example wherein we have assumed that it is desired to operate the system in reconfigured mode R1, and furthermore it is desired to address MMS. A signal MBA1130 is applied to a jumper cap 853; the signal MBA1130 indicates address bit 11 is applied to jumper cap 853 from this signal is developed in the IOC and is transmitted to the MSS. As shown on FIGS. 4B and 4C the particular combination of bits 11 and 28 in the pattern shown and discussed supra are utilized to select a desired module in reconfigured state R1 and R2. Bit 28 is applied on FIG. 2, gate 840 (MBAZ840). Signal MBA1130 (i.e., address bit 11 from the IOC to the MSS) emerges as signal NIRC4I0 (i.e., IOC reconfiguration bit number 4). Signal NIRC410 is applied to AND gates 859 and 862. Following the signal through AND gate 862 it is seen that it is enabled and applies the signal to inverter 863 and to one input of AND gate 876. The other input to AND gate 876 is signal NREC derived from signal UNRCI 1S and indicates reconfigured mode R1. (The dash-dot lines are in cluded to make it more convenient to follow the path of various signals in reconfigured state R1). With both input signals on AND gate 876 high, it is enabled and a high signal is applied to amplifier 878 generating a signal NIS2N10 which indicates that the lower modules in the address range are selected. Signal NISZN 10 is applied to AND gate 840 as one of its inputs. The other input signals to AND gate 840 are described below. Signal NRECY13 is an input signal to AND gate 840 and indicates main memory is in a reconfigured state. Signal NRECY13 arrived to AND gate 840 via the following path: pin 802, AND gate 805, amplifier 808, AND gate 810, amplifier 812, AND gate 819, and amplifier 824. Another input signal applied to AND gate 840 is NIOCDIO which indicates that the input/output control unit (IOC) has control of the main storage sequencer (MSS). The final input signal to AND gate 840 is MBA2810 which indicates bit 28 is applied and is one of the bits necessary together with bit 11 to select module 2 in reconfigured state R1. With all these input signals high AND gate 840 is enabled and provides an input signal for AND gate 837. The other input signal I to AND gate 837 is signal MNBZ200 which is high when the statement it represents, (i.e., main memory module 2 busy not) is true. Assuming module 2 is not 5 busy signal MNBZ200 is high thus enabling AND gate 837 and applying a high signal to amplifier 838 thus generating a Go signal NMGOOIT for main memory module 2, i.e., MMS.

By similar analysis of FIG. 11A, it can be shown that any memory module can be addressed in any configuration.

GLOSSARY OF TERMS S IGNAL LOG IC NAME DEFINITIONS NBUFflll BUFFER 0R CP ASSIGNED FLAG SIGNAL 1 NBUFfllZ 2 NBUFI3 3 NBUFfllS 5 NBUFfllG 6 NMA211R MMS ADDRESS BITS 21 NMA221R 22 NMA231R 23 NMGOQlfl MAIN MEMORY MODULE a G0 SIGNAL NMGUIIU 1 GO SIGNAL NMGOZlfl 2 GO SIGNAL NMGO3lfl 3 GO SIGNAL MNBzqufl MAIN MEMORY MODULE a BUSY-NOT MNBZlflfl l BUSY-NOT MNBzzgg 2 BUSY-NOT MNBZ3H 3 BUSY-NOT UBAP33 CP ADDRESS PARITY BIT 3 NUABBlfl CP ADDRESS BYTE 2 PARITY CHECK UBA283fl CP ADDRESS BIT 2s NCONLlfl CP ONLY ASSIGNED FLAG SIGNAL NCPODlfl CP GO DELAYED NUSZNlfl CP LOWER MODULE SELECT FOR RECONFIGURED MODE NUSZAlfl CP UPPER MODULE SELECT FOR RECONFIGURED MODE NUGORlfl CP GO RESET SIGNAL MBAP 2 13 IOC ADDRESS PARITY CHECK BIT 2 SIGNAL LOGIC NAME DEFINITIONS" NIA3BI1T NIOCIJlfl NIOCA2U NMIORZQ NIOCDlfl NISZNIH NISZAlfl NIOCTIU NBuFAza BNMGOlfl BNAF33 NBA3B1U NBONLll NMBGOl/d MBRWSlfJ NBSZNlfl NBSZAlB NRECN13 NRECY13 NRECNl4 NRECY14 NMSSZlIJ NAPCBIE NIAPClfl NAPMDlH NAP3JJ1H NMSSZ42 UBA273B NMA211T NMA221T IOC ADDREEFQTIIE 3 PARITY CHECK IOC CONTROL FUNCTION ASSIGNMENT FLAG IOC ALONE NOT IOC RESERVATION NOT IOC GO DELAYED IOC LOWER MODULE ELECT FOR RECONFIGURED MODE IOC UPPER MODULE SELECT FOR RECONFIGURED MODE IOC GO TO MSS BUFFER ALONE-NOT BUFFER GO BUFFER ADDRESS PARI'I'Y BIT 3 BUFFER ADDRESS BYTE 3 PARI'I'Y CHECK BUFFER ONLY ASSIGNMENT FLAG SIGNAL IOC GO SIGNAL TO BUFFER IOC WRITE SIGNAL BUFFER LOWER MODULE SELECT FOR RECONFIGURED MODE BUFFER UPPER MODULE SELECT FOR RECONFIGURED MODE RECONFIGURATION MODE NOT MMS RECONFIGURED YES (Amnlifier 3) MMS NON-RECONFIGURED MODE MMS RECONFIGURED YES (Amplifier 4) MMS BUSY ADDRESS PARITY CHECK INHIBIT IOC ADDRESS PARITY CHECK INHIBIT ADDRESS P RITY MODE IOC ADDRESS BYTE 3 PARII'Y C ECK MSS NOT BUSY CP ADDRESS BIT 27 ADDRESS BIT 21 TO MMS INTERFACE SIGNAL 22 TO MMS INTERFACE SIGNAL 23 TO MMS INTERFACE SIGNAL SIGNAL LOGIC NAME NMA241T NMA251T NMA261T NMGOfllT NMGOllT NMGOZIT NMG031T XNZl MBAZllS NMGORlS MBA22lS MBA23lS MBA24lS MBAZSIS MBA261S MBA271S MBA281S NXU MBAPZlS MBAP31S MBGURlS MBRWSIS MBMGOIS MMP481JJ MMP491fl MMPBOlfl MMPSllIJ MMP521J6 MMPSBlfl MMP54Ip 25 TO MMS INTERFACE SIGNAL 26 TO MMS INTERFACE SIGNAL INTERFACE GO SIGNAL TO MSS MODULE 0 II II II II II II 1 I I! II II II N 2 II II II II II II 3 INTERFACE GO SIGNAL NOT USED TO MSS MODULE I. II II II II II II II IOC ADDRESS TO MSS BIT 21 GENERAL GO RESET INTERNAL MSS IOC ADDRESS BIT 22 TO MSS 23 TO MSS 24 TO MSS 25 TO MSS 26 TO MSS 27 TO MSS 28 TO MSS NOT USED IOC ADDRESS PARITY BIT 2 TO MSS 3 TO MSS MSS GO RESET TO IOC IOC READ OR WRITE TO MSS IOC GO SIGNAL THRU MSS TO BUFFER IOC WRITE DATA TO THE PARITY CHECKER BIT 48 SIGNAL LOGIC NAME DEFINITIONS IOC WRITE DATA PARITY CHECK BYTE IOC BYTE Q PARITY ERROR CHECK IOC WRITE DATA BYTE 6 PARITY BUFFER BYTE [J PARITY ERROR CHECK CP WRITE DATA TO THE PARITY CHECKER BIT 48 SIGNAL LOGIC NAME BNPSS If i BNP561H BNP571 BNP581 BNP59ljJ BNP601 BNP611 BNP621 BNP631 BNPP71 NICYClfl NCCYClfl NBcYclQI NIETMlJJ NINETUJ NIAPBlQ MNIMElfl NIWESlfl NI0C34 NCETMIQI NCNETlQ NUAPBlJJ MNCMElQ NcwEsw ncpmzlas MNWABlfl UBWAB3 UNINT3IJ NIDPCll NBETMUJ NMAKCQQ 4 DEFINITIONS I II II II II II II II II CP WRITE DATA TOW THE PARITY CHECKER BIT CP WRITE DATA PARITY CHECK BYTE 7 IOC CYCLE INTERNALLY GENERATED CP CYCLE INTERNALLY GENERATED BUFFER CYCLE INTERNALLY GENERATED IOC WRITE ABORT LATCH IOC RETRYABLE ERROR LATCH IOC PARITY CHECK INHIBIT IOC MASK PARITY ERROR NON-RETRYABLE ERROR STROBE IOC CONTROL SIGNAL TO MSS CP WRITE ABORT LATCH CP RETRYABLE ERROR LATCH CP PARITY CHECK INHIBIT CP MASK PARITY ERROR NON-RETRYABLE ERROR STROBE CP ASSIGNED CONTROL OF THE MSS IOC WRITE ABORT CPU WRITE ABORT CP INITIALIZE INHIBIT DATA PARITY CHECK BUFFER WRITE ABORT LATCH MEMORY ACKNOWLEDGE CONTROL NOT l5 SIGNAL LOGIC NAME NIAKs2a NBAKSZIJ NCAKs2 NINXMljZ! NIOCTlfl NUNXMlfi NCPQQI 6 NBNXMljJ NBUFfllS NUSEClfl NBNERlfl NBERSlH NBRERI J NIBPSlfl NIBP7lfl NBBP619I NBBP71,0

NMACKlfl NBACKlH NUACKlH NMBZEQJZ NMBZlflQ NMBZZQH NMBZBIM NTACKIQ NBNEMlH NIAPClfl NIDPClfl DEFINITIONS IOC ACKNOWLEDGE NOT BUF.

CPU I IOC NON-ExIsTENT MEMORY CHECK IOC GO SIGNAL CP NON-ExIsTENT MEMORY CHECK CP ASSIGNED CONTROL OF THE Mss BUFFER NON-EXISTENT MEMORY CHECK BUFFER ASSIGNED CONTROL OF THE Mss CP SINGLE ERROR CORR.

BUFFER NON-RETRYABLE ERROR BUFFER ERROR STROBE BUFFER RE-I'RYABLE ERROR IOC BAD BYTE 6 PARITY CHECK II II II '7 II II BUFFER BYTE 6 PARITY ERROR CHECK n u 7 u n n IOC ACKNOWLEDGE BUF.

CPU

MMS MODULE H BUSY NOT II II 1 'I II II N 2 II H II II 3 II II MMS ACKNOWLEDGE WHICH RESETS MSS BUSY BUFFER NON-EXISTENT MEMORY CHECK INHIBIT ADDRESS PARITY CHECK INHIBIT DATA PARITY CHECK SIGNAL LOGIC NAME NBRDSlfl NRECllfl NRECZlfl NRECYll NRECY12 NRECY13 NRECYl4 NRECNll NRECNl2 NRECN13 NRECN14 NBNETIQ MBA83I MBA9 30 MBA13J6 MBAllBfi MBA123U MBA133 MBA143I5 msszAm NBSZNlfl NINXMlfl NUNXMIIJ NBNXMlfl NINM21 NINMllfl NINMfJlfl DEFINITIONS BUF/CP READ STROBE RECONFIGURATION MODE Rl RECONFIGURATION MODE R2 MMS RECONFIGURATION MODE DRIVER 1 II II II II 2 II II II II 3 II II II II 4 II II II II II 2 II II II II II 3 II II II II II 4 BUF. NON-RECONFIGURATION ERROR LATCH STROBE l IOC TO MSS ADDRESS BIT 8 BUF. UPPER MODULE SELECT IN RECONFIGURED MODE BUF. LOWER MODULE SELECT IN RECONFIGURED MODE IOC NON-EXISTENT MEMORY CHECK BUF.

IOC NON-EXIS'IENT MEMORY CHECK BIT 2 u u u n n n l n n II II n g GROUND LOG I CAL l IOC TO MSS ADDRESS BIT 8 II II II II II 9 SIGNAL LOGIC NAME DEFINITIONS MBA13 IOC TO Mss ADDRESS BIT 1Q MBAl l 3 H 1 l MBA12315 12 MBAl 3 3 E l 3 MBAl 4 313 l 4 NIRCIJlfl IOC RECONFIGURATION BIT 0 NIRCllfl 1 NIRCZlJJ 2 NIRC3lp 3 NIRC4I 4 NUNM21 CP NON-EXISTENT MEMORY CHECK BIT 2 NUNMlllJ 1 NUNMQIE a NURCfllfl CP RECONFIGURATION BIT 0 NURC 1 1E! l NURCZIQ 2 NURC31 3 NURC41B 4 NBNMZlfl BUFFER NON-EXISTENT MEMORY CHECK BIT 2 NBNMllIJ NBNMQIE NBRC2 1B BUFFER RECONFIGURATION BIT 2 BNAl43fl CP/BUFFER ADDRESS BIT 14 NBACIIE BUFFER RECONFIGURATION BIT 1 NBRCflljJ $3 NBRC31B 3 NBRC41E 4 NINM31IJ IOC NON-EXISTENT MEMORY CHECK BIT 3 NINM4ljJ NINMSlfl NI II II II II II II SIGNAL LOGIC NAME NINMGlfl Numb 14113 NUNMSIJJ NUNM31 NUNMSlIJ NUNM71 NUNM61 NBNM llfl NBNMSljZ! NBNMBlIJ NBNM71IZ Nam 1619 NUMREIS NURERILS NUNERIS NUWRClS UNMMNlS UNMMQlS UNMMllS UNMMZlS NUNEMlS UNR241S UNRCllS NMACKlS NMRDSlS NMRERlS NMNERlS NMERSlS NMWRClS CP NON-EXISTENT MEMORY CHECK BIT 4 H M Mr rmflfim 22 DEFINITIONS u I A II Ran II il ill I! 7 II n I! 6 BUFFER NON-EXISTENT MEMORY CHECK BIT 4 MMS TO CP READ DATA ERROR MMS TO CP RETRYABLE ERROR MMS TO CP NON-RETRYABLE ERROR MMS TO CP WRITE CANCELLED CP MODE REQUEST (-1) CP MODE REQUEST Q CP MODE REQUEST 1 CP MODE REQUEST 2 MMS TO CP NON-EXISTENT MEMORY CP TO MMS RECONFIGURED MODE CP TO MMS RECONFIGURED MODE MMS TO I/O MEMORY ACKNOWLEDGE MMS TO I/O READ STROBE MMS TO I/O RETRYABLE STROBE MMS TO I/O NON-RETRYABLE ERROR MMS TO I/O ERROR STROBE MMS TO I/O WRITE CANCELLED SIGNAL LOGIC NAME DEFINITIONS MNACKlT MMS TO MSs ACKNOWLEDGE INTERFACE SIGNAL MNRDSlT MMS TO Mss READ STROBE INTERFACE SIGNAL MNRERIT MMS TO MSS RETRYABLE ERROR INTERFACE IGNAL MNNERlT MMS TO MSS NON-RETRYABLE ERROR INTERFACE SIGNAL MNERSlT MMS TO MSS ERROR STROBE INTERFACE SIGNAL MNWRClT MMS TO MSS WRITE CANCELLED INTERFACE SIGNAL MNSEClT MMS TO MSS SINGLE ERROR CORRECT INTERFACE SIGNAL NMMMfIlT MSS TO MMS DIAGNOSTIC MODE BIT 0 INTERFACE SIGNAL NMMM11T MSS TO MSS DIAGNOSTIC MODE BIT 1 INTERFACE SIGNAL NMMM21T MSS To MMS DIAGNOSTIC MODE BIT 2 INTERFACE SIGNAL MNBZfllT MMS To Mss MODULE 0 BUSY INTERFACE SIGNAL MNBZllT 1 MNBZZlT I 2 MNBZ31T A 3 BNA8 3p CPU/BUFFER TO MSS ADDRESS BIT 8 BNAHQ 3Q 9 BNA13 10 BNA113 11 BNA123pI 12 BNAl33IZ! 13 BNA14 3 p 14 BNAlSBJ?! 15 BNA163D l6 BNA173IJ 17 BNA183JJ 1s BNA19 312! 19 BNA231J I 20 BNA213JZ I 21 BNA223H I 22 233g u n n n u n 23 25. I SIGNAL LOGIC NAME DEFINITIONS MBA8 3;; IOC TO MSS ADDRESS BIT 8 MBAIZ|93JJ 9 MBA-1H3}?! 10 MBAll3fl 11 MBA123 "V 12 MBA1339 13 MBA143 14 MBAI532! 15 MBAl63H l6 MBA173 17 MBA1831J 1s MBA193J6 19 MBA23H 2o MBA213IZI 21 MBA223IJ 22 MBA233JJ 23 MBA243,0 24

MBA253IJ 25 MBA263 26 MBA273 27 MBA283 28 NBAPBlfl BUFFER ADDRESS PARI'IY CHECK NIAPBlfl Ioc NUAPBlfl CPU MBAPllS Ioc ADDRESS BYTE' 1 PARITY BIT MBAP23JJ 2 NIAlBlIJ IDc ADDRESS BYTE l PARI'I'Y CHECK NIA2B19 2 NIA3Blfl 3 NIAPClfl INHIBIT ADDRESS PARII'Y CHECK SIGNAL LOGIC NAME II II II 2 II II BUFFER ADDRESS BYTE l PARITY BIT II II II 2 II II BUFFER ADDRESS BYTE l PARITY CHECK CP WRITE MASK BIT 0 MAIN MEMORY DATA PARITY CHECK BIT 48 SIGNAL LOGIC NAME NNPGllfl NNP621IJ NNP631 NNPP71 NNPF6I MNWRBIIJ NMIORZQ MBRWSlQ! UNRWSlIJ UNINT3 UNWAR3 NCWABIIZ NIWABlIJ NIAPClIJ MNIMEIU UNMXP3 MNCMElfl NIDPCIQJ NMBP61 NMBP7lj6 NIOCD1 NMAKSlfl NINBYlQ! NCPQfllS NCNBYlfl NBUFGlS NBNBYlIZ NETMSlQ NCETRljZ NIETRIQ! NBETRIQI DEFINITIONS MAIN MEMORY DATA PARITY CHECK BIT 61 MAIN MEMORY DATA PARI'I'Y CHECK BYTE 7 IOC WRITE ABORT IOC RESERVATION NOT IOC READ/WRITE SIGNAL CP INITIALIzE CP WRITE ABORT WRITE ABORT IOC WRITE ABORT IOC ADDRESS PARITY CHECK INHIBIT IOC NON-RETRYABLE ERROR LATCH CP WRITE MASK PARITY BIT CP NON-RETRYABLE ERROR LATCH INHIBIT DATA PARITY CHECK READ DATA BYTE 6 PARITY CHECK II II II 7 II II IOC GO DELAYED MEMORY ACKNOLWEDGE SIGNAL IOC CYCLE IN MSS IOC CONTROL FUNCTION CP CYCLE IN MSS BUFFER CONTROL FUNCTION BUFFER CYCLE IN MSS CONTROL FROM TIMING CP CONTROL FOR ERROR IOC CONTROL FOR ERROR BUFFER CONTROL FOR ERROR SIGNAL LOGIC NAWE NBNE'IljZ NIAKSZfl NcAKszg NBAKSZQ NIRDSlJJ NIRDRlfl NCRDSlfl NcRDRm NBRDSLG NBRDRlIJ NIRDLlfiI NCRDLlfl NIPcsm NIPCRlfl NCPCSlfl NcPcRm NBPCSIIJ NBPCRlJJ NIPCLlfl NcPcLm NBPcLm DEFINITIONS II II II II N IOC READ DATA COMPARE CNTL.

CP CNTL.

BUF.

" CNTL.

IOC RETRYABLE .ERROR STROBE II II II II II II IOC WRITE DATA BIT 0 u u u vi 9 l SIGNAL LOGIC NAME DEFINITIONS IOC WRITE DATA BIT 11 CP WRITE DATA BIT 0 DATA BIT 0 IOC WRITE DATA PARITY CHECK BIT 0 

1. In combination with a computer memory system comprised of four memory modules arranged in an four-way interleaved addressing configuration mode, an electrical reconfiguration network for dynamically varying under program control the configuration mode of said four memory modules from four way interleaved addressing configuration to two-way interleaved addressing configuration where k is an integer equal to m/2, said reconfiguration network comprising: a. first circuit means responsive to first predetermined bits in a first instruction from a program under execution for generating first reconfiguration signals, indicative of a desired predetermined state of interleaved addressing configuration; b. second circuit means responsive to second predetermined addressing bit positions in a second instruction of a program under execution for generating second reconfiguration signals; c. third means, responsive to said second means, for addressing predetermined ones of said four modules in normal four-way interleaved addressing configuration; and d. fourth circuit means, coupled to said first and second circuit means, for dynamically varying, in response to said first or second reconfiguration signals, the configuration mode of said four modules from four-way interleaved addressing configuration to two-way interleaved addressing.
 2. The combination as recited in claim 1 wherein said four-way interleaved addressing mode is a normal mode and the two-way interleaved addressing mode is a reconfigured mode and wherein there are two reconfigured modes R1 and R2.
 3. The combination as recited in claim 2 wherein the four memory modules in the normal four-way mode are MMS0, MMS1, MMS2 and MMS3 and wherein reconfigured mode R1 comprises MMS2 and MMS3 occupying a first half of the total addressable space and MMS0 and MMS1 occupying a second half of the total addressable space.
 4. The combination as recited in claim 3 wherein the reconfigured mode R2 comprises MMS0 and MMS1 occuppying the first half of the total addressable space and MMS2 and MMS3 occupying the second half of the total addressable space.
 5. The combination as recited in claim 4 being reconfiguration mode R1 and is utilized when a fault is located in either module MMS2 or MMS3 or in both MMS2 and MMS3, and reconfiguration mode R2 being utilized when a fault located in either module MMS0 or MMS1 or in both MMS0 and MMS1.
 6. A method of reconfiguring a computer memory system comprised of four memory modules arranged in a four-way interleaved addressing configuration mode, to a two-way interleaved addressing configuration, said method comprising the steps of: a. generating, in response to first predetermined bits from a first instruction of a program under execution, first reconfiguration signals indicative of a desired predetermined state of interleaved addressing configuration; b. generating, in response to predetermined address bit positions of a second instruction of a program under execution, second reconfiguration signals for addressing any one of said four modules in any one of said two-way interleaved addressing configurations; and, c. applying said first or second reconfiguration signals to said computer memory system to control said computer memory system for varying the four-way interleaved addressing configuration mode to two-way interleaved addressing configuration. > 